// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Custom/SimpleGrabPassBlur" {
    Properties{
        _Color("Main Color", Color) = (1,1,1,1)
        _BumpAmt("Distortion", Range(0,128)) = 10
        _MainTex("Tint Color (RGB)", 2D) = "white" {}
        _BumpMap("Normalmap", 2D) = "bump" {}
        _Size("Size", Range(0, 20)) = 1
    }

        Category{

            // We must be transparent, so other objects are drawn before this one.
            Tags { "Queue" = "Transparent" "IgnoreProjector" = "True" "RenderType" = "Opaque" }


            SubShader {

                // Horizontal blur
                GrabPass {
                    Tags { "LightMode" = "Always" }
                }
                Pass {
                    Tags { "LightMode" = "Always" }

                    CGPROGRAM
                    #pragma vertex vert
                    #pragma fragment frag
                    #pragma fragmentoption ARB_precision_hint_fastest
                    #include "UnityCG.cginc"

                    struct appdata_t {
                        float4 vertex : POSITION;
                        float2 texcoord: TEXCOORD0;
                    };

                    struct v2f {
                        float4 vertex : POSITION;
                        float4 uvgrab : TEXCOORD0;
                    };

                    v2f vert(appdata_t v) {
                        v2f o;
                        o.vertex = UnityObjectToClipPos(v.vertex);
                        #if UNITY_UV_STARTS_AT_TOP
                        float scale = -1.0;
                        #else
                        float scale = 1.0;
                        #endif
                        o.uvgrab.xy = (float2(o.vertex.x, o.vertex.y * scale) + o.vertex.w) * 0.5;
                        o.uvgrab.zw = o.vertex.zw;
                        return o;
                    }

                    sampler2D _GrabTexture;
                    float4 _GrabTexture_TexelSize;
                    float _Size;

                    half4 frag(v2f i) : COLOR {
                        //                  half4 col = tex2Dproj( _GrabTexture, UNITY_PROJ_COORD(i.uvgrab));
                        //                  return col;

                                            half4 sum = half4(0,0,0,0);
                                            #define GRABPIXEL(weight,kernelx) tex2Dproj( _GrabTexture, UNITY_PROJ_COORD(float4(i.uvgrab.x + _GrabTexture_TexelSize.x * kernelx*_Size, i.uvgrab.y, i.uvgrab.z, i.uvgrab.w))) * weight
                                            sum += GRABPIXEL(0.05, -4.0);
                                            sum += GRABPIXEL(0.09, -3.0);
                                            sum += GRABPIXEL(0.12, -2.0);
                                            sum += GRABPIXEL(0.15, -1.0);
                                            sum += GRABPIXEL(0.18,  0.0);
                                            sum += GRABPIXEL(0.15, +1.0);
                                            sum += GRABPIXEL(0.12, +2.0);
                                            sum += GRABPIXEL(0.09, +3.0);
                                            sum += GRABPIXEL(0.05, +4.0);

                                            return sum;
                                        }
                                        ENDCG
                                    }
            // Vertical blur
            GrabPass {
                Tags { "LightMode" = "Always" }
            }
            Pass {
                Tags { "LightMode" = "Always" }

                CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag
                #pragma fragmentoption ARB_precision_hint_fastest
                #include "UnityCG.cginc"

                struct appdata_t {
                    float4 vertex : POSITION;
                    float2 texcoord: TEXCOORD0;
                };

                struct v2f {
                    float4 vertex : POSITION;
                    float4 uvgrab : TEXCOORD0;
                };

                v2f vert(appdata_t v) {
                    v2f o;
                    o.vertex = UnityObjectToClipPos(v.vertex);
                    #if UNITY_UV_STARTS_AT_TOP
                    float scale = -1.0;
                    #else
                    float scale = 1.0;
                    #endif
                    o.uvgrab.xy = (float2(o.vertex.x, o.vertex.y * scale) + o.vertex.w) * 0.5;
                    o.uvgrab.zw = o.vertex.zw;
                    return o;
                }

                sampler2D _GrabTexture;
                float4 _GrabTexture_TexelSize;
                float _Size;

                half4 frag(v2f i) : COLOR {
                    //                  half4 col = tex2Dproj( _GrabTexture, UNITY_PROJ_COORD(i.uvgrab));
                    //                  return col;

                                        half4 sum = half4(0,0,0,0);
                                        #define GRABPIXEL(weight,kernely) tex2Dproj( _GrabTexture, UNITY_PROJ_COORD(float4(i.uvgrab.x, i.uvgrab.y + _GrabTexture_TexelSize.y * kernely*_Size, i.uvgrab.z, i.uvgrab.w))) * weight
                                        //G(X) = (1/(sqrt(2*PI*deviation*deviation))) * exp(-(x*x / (2*deviation*deviation)))

                                        sum += GRABPIXEL(0.05, -4.0);
                                        sum += GRABPIXEL(0.09, -3.0);
                                        sum += GRABPIXEL(0.12, -2.0);
                                        sum += GRABPIXEL(0.15, -1.0);
                                        sum += GRABPIXEL(0.18,  0.0);
                                        sum += GRABPIXEL(0.15, +1.0);
                                        sum += GRABPIXEL(0.12, +2.0);
                                        sum += GRABPIXEL(0.09, +3.0);
                                        sum += GRABPIXEL(0.05, +4.0);

                                        return sum;
                                    }
                                    ENDCG
                                }

                                            // Distortion
                                            GrabPass {
                                                Tags { "LightMode" = "Always" }
                                            }
                                            Pass {
                                                Tags { "LightMode" = "Always" }

                                                CGPROGRAM
                                                #pragma vertex vert
                                                #pragma fragment frag
                                                #pragma fragmentoption ARB_precision_hint_fastest
                                                #include "UnityCG.cginc"

                                                struct appdata_t {
                                                    float4 vertex : POSITION;
                                                    float2 texcoord: TEXCOORD0;
                                                };

                                                struct v2f {
                                                    float4 vertex : POSITION;
                                                    float4 uvgrab : TEXCOORD0;
                                                    float2 uvbump : TEXCOORD1;
                                                    float2 uvmain : TEXCOORD2;
                                                };

                                                float _BumpAmt;
                                                float4 _BumpMap_ST;
                                                float4 _MainTex_ST;

                                                v2f vert(appdata_t v) {
                                                    v2f o;
                                                    o.vertex = UnityObjectToClipPos(v.vertex);
                                                    #if UNITY_UV_STARTS_AT_TOP
                                                    float scale = -1.0;
                                                    #else
                                                    float scale = 1.0;
                                                    #endif
                                                    o.uvgrab.xy = (float2(o.vertex.x, o.vertex.y * scale) + o.vertex.w) * 0.5;
                                                    o.uvgrab.zw = o.vertex.zw;
                                                    o.uvbump = TRANSFORM_TEX(v.texcoord, _BumpMap);
                                                    o.uvmain = TRANSFORM_TEX(v.texcoord, _MainTex);
                                                    return o;
                                                }

                                                fixed4 _Color;
                                                sampler2D _GrabTexture;
                                                float4 _GrabTexture_TexelSize;
                                                sampler2D _BumpMap;
                                                sampler2D _MainTex;

                                                half4 frag(v2f i) : COLOR {
                                                    // calculate perturbed coordinates
                                                    half2 bump = UnpackNormal(tex2D(_BumpMap, i.uvbump)).rg; // we could optimize this by just reading the x  y without reconstructing the Z
                                                    float2 offset = bump * _BumpAmt * _GrabTexture_TexelSize.xy;
                                                    i.uvgrab.xy = offset * i.uvgrab.z + i.uvgrab.xy;

                                                    half4 col = tex2Dproj(_GrabTexture, UNITY_PROJ_COORD(i.uvgrab));
                                                    half4 tint = tex2D(_MainTex, i.uvmain) * _Color;

                                                    return col * tint;
                                                }
                                                ENDCG
                                            }
                                        }
        }
}